Internal photon-to-electron-conversion

For solar cells, the efficiency is given under irradiation with a solar spectrum under air mass 1.5 (AM 1.5) [65] in terms of power conversion efficiency or internal photon-to-electron conversion efficiency (ICPE) [66]. Characteristic parameters that are often used are the open circuit voltage Voc, the short circuit current density /sc, and the fill factor, given by... 

Photomultiplier Conversion Dynode This detector is similar to the electron multiplier in that the ions strike a dynode resulting in the emission of electrons. However, these electrons are now made to strike a phosphorus screen. This screen releases photons when electrons strike it. These photons are now detected by a photomultiplier (see chapter 8, figure 8.17). The primary advantage of this setup is that the photomultiplier tube is housed in vacuum. This removes the possibility of any contamination from the internal environment. Thus, while the photomultiplier conversion dynode has sensitivity similar to that of electron multiplier, it has a higher life. For this reason these detectors are becoming more popular. Figure 15.9 describes the working of a photomultiplier conversion detector. 

Another form of radiationless relaxation is internal conversion, in which a molecule in the ground vibrational level of an excited electronic state passes directly into a high vibrational energy level of a lower energy electronic state of the same spin state. By a combination of internal conversions and vibrational relaxations, a molecule in an excited electronic state may return to the ground electronic state without emitting a photon. A related form of radiationless relaxation is external conversion in which excess energy is transferred to the solvent or another component in the sample matrix. 

The iatensity of a conversion fine can be expressed relative to that of the associated y-ray as the internal-conversion coefficient (ICC), denoted as d. For example, is the ratio of the number of electrons emitted from the K atomic shell to the number of photons emitted. For the other atomic levels, the corresponding conversion coefficients are denoted by (X, The total conversion coefficient is a = n, where the sum iacludes all atomic... 

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